Refractor and reflector system for vertically mounted arc lamp



June 20, 1967 FRANCK 3,327,109

REFRACTOR AND REFLECTOR SYSTEM FOR VERTICALLY MOUNTED ARC LAMP Filed Oct. 22, 1964 INVENTOR X akr [kw/vex ATTORNEYS United States Patent O 3,327,109 REFRACTOR AND REFLECTOR SYSTEM FOR VERTICALLY MOUNTED ARC LAMP Kurt Franck, Newark, Ohio, assignor to Holophane Company, Inc., New York, N.Y., a corporation of Delaware Filed Oct. 22, 1964, Ser. No. 405,703 1 Claim. (Cl. 240-415) The present invention relates to luminaires.

In particular, the present invention relates to luminaries intended to be used with mercury lamps.

For reasons of best operating conditions it is often preferable to use mercury lamps in a vertical burning position, but because of the length of the mercury arc, especially when it is mounted vertically, it is diflicult to achieve a sharp and narrow light beam which extends in a vertical direction and which is concentrated in a manner which is required for street and area luminaires.

It is therefore a primary object of the present invention to provide a solution to the above problem.

Thus, it is an object of the invention to provide a luminaire capable of utilizing a mercury lamp, preferably with its are extending vertically, in such a manner as to be able to achieve a highly concentrated light beam suitable for use with a street or area luminaire.

Furthermore, it is an object of the present invention to provide a luminaire which will have maximum candle power at the desired beam angle and with a sharp cut-01f above the desired beam angle.

The invention is illustrated by way of example in the accompanying drawing which forms part of the application and in which one possible structure according to the present invention is schematically illustrated.

The luminaire shown in the drawing includes a mercury lamp 12 capable of being energized in any known way from a suitable source of current, and this lamp 12 is mounted in a vertical position so that when the lamp 12 is energized it will have a vertically extending elongated mercury are 14 provided with a lower end A and an upper end B. The lamp 12 is mounted within a reflector means 16 having an inner reflecting surface, and situated in front of the lamp 12 is a refractor means 18 in a form of a transparent plate of glass or plastic having a flat inner surface 20 directed toward the lamp 12 and a front surface having ridges 22, as illustrated, and a depressed front surface 24 which, it will be noted, is at the elevation of the lower end A of the arc 14. The refractor 18 may be supported at its opposite sides by side walls of the reflector 16.

The drawing illustrates ray traces from the ends A and B of the are 14, those ray traces which extend at the desired beam angle being shown in solid lines, while those which are below the beam angle are shown in dash lines.

Thus, it will be seen from the drawing that the upper end B of the vertical arc 14 is situated at the focal point of the reflector means 16, so that the rays 26 issuing from the end B will all be reflected by the reflector means 16 in a direction perpendicular to the direction in which the beam 14 extends, and in the illustrated example since the beam 14 extends vertically the rays 26 will extend horizontally. On the other hand, it will be seen that all of the rays 32 from the other end A of the are 14 are reflected at lower angles than the rays 26.

The refractor means 18 cooperates with the lower end A of the vertical are 14 so as to directly retract light therefrom in a horizontal direction perpendicular to the vertical are 14, and thus the horizontal ray traces 28 refracted from light received from the lower end A of the are 14 are illustrated in the drawing. It is to be noted that the rays 30 from the upper end B are refracted by the refractor 18 at angles lower than the desired angle of the rays 28. Thus, with this construction the refractor 18 will with its elongated ridges 22 and its intermediate portion 24 cooperate with the light issuing from the end A to provide the concentrated beam 28, and the reflector means 16 will direct the rays 26 in the same direction as the rays 28, so that in this way a highly concentrated beam is achieved while light from the intermediate portion of the are 14 and from the end thereof for which the reflector or refractor is not designed (the end A for the reflector 16 and the end B for the refractor 18) is directed below the beam angle.

Thus, it will be seen that with the structure of the inven tion there are provided both reflected and directly refracted beam components derived, not from the center of the arc, but from the ends thereof, respectively. In this way full light concentration is obtained for the structure of the invention, and for reasons of geometry the light from the end of the arc and intermediate points thereof for which the particular reflector or refractor are not designed will not be fully concentrated. Therefore, the light from the end of the beam for which the reflector or refractor is designed can be directed with full concentration at the desired beam angle while the remaining light is provided at lower angles giving only partial concentration, so that maximum candle power is achieved at the desired beam angle with sharp cut-0ft above this desired beam angle.

What is claimed is:

In a luminaire, a mercury lamp having a vertical arc, reflector means cooperating with one of the ends of the are for directing light received therefrom in a horizontal direction and for directing light received from all other parts of the arc in a direction below said horizontal direction, and refractor means situated in front of said lamp and cooperating with the other end of said arc thereof for directing light received from said other end also in a horizontal direction, said refractor means directing substantially all of the remaining light from said are in a direction below said horizontal direction.

References Cited UNITED STATES PATENTS 8/1941 Winkler et al. 24041.3 6/1965 McPhail 24025 

